You're going to love it here, it's a great forum with a lot of supportive people. I bet you're so excited about your new bike. They way to best help out with the sore butt issue is to ride often but not overdo long rides to begin with. Just like anything else, it will toughen up and your body parts will get used to riding. If you still have pain a couple of weeks into this then you might want to think about a different saddle, but give the stock saddle a chance, you might like it.

I would expect some soreness in the first few rides since it has been such a long time.

Good luck and post some pictures of your bike when you get it!